Retort for oil-bearing shales



Oct. 31, 1967 H. F. WEST RETORT FOR OIL-BEARING SHALES Fi led Oct. 51,1963 INVENTOR.

HOWARD F. WEST W .ATTO NEY United States Patent 3,350,280 RETORT FOROIL-BEARING SHALES Howard F. West, Shaker Heights, Ohio, assignor, bymesne assignments, to The Standard Oil Company, Cleveland, Ohio, acorporation of Ohio Filed Oct. 31, 1963, Ser. No. 320,450 3 Claims. (Cl.20299) The present invention relates to improvements in rotatablevessels for treatment such as grinding and drying, heating,dry-distillation or cooling, of piece-shaped material of different kindsby means of heated or cooled loose balls which are brought into directcontact with the mate rial to be treated.

The present invention is particularly useful in the drydistillation ofsuch materials as bituminous shales and the like, peat, saw-dust, woodchips, coal and other distillable substances, but is especially usefulin the dry-distillation of oil-bearing shales.

It is an object of the present invention to provide an apparatus usefulin the distillation of oil-bearing shales and the like at lowtemperatures, with a rapid transfer of the distilling heat to thematerial being distilled, and without any necessity for employing theexpensive heating surfaces heretofore required because of the slow andinefficient heat transfer of many of the prior low temperaturedistillation procedures.

In order to recover oil from oil shale and similar oilbearing solids, itis necessary to retort them to break down the solid or semi-solidhydrocarbon or oil-forming materials such as kerogen. The hydrocarbons,thus broken down to products of moderate molecular weight, are drivenoff as vapors or entrained liquids. Oil shale, for example, is usuallybroken into small lumps or particles and then heated to a temperature ofabout 850-l000 F. or more for a sufficient time to convert the kerogenand to recover the desired oil products.

It has previously been proposed to treat oil shale by heating it in afirst rotating furnace by means of loose heat-carrying bodies andwherein said heat-carrying bodies are first heated in asecond rotatingfurnace by combustion of fuel in admixture therewith, the heat-carryingbodies circulating through both furnaces. It is not necessary that tworotating furnaces be employed so long as the heat-carrying bodies areheated by some external means and then brought into contact in arotating furnace with the oil shale to cover grinding, heat transfer andretorting of the shale.

The present invention involves an apparatus presenting certainimprovements on those used in the processes just described which will bedescribed in detail.

The present invention makes effective use of the highly eflicient heattransfer from hot solid bodies and preferably attrition resistant solidbodies to cooler solids. At the same time it avoids the disadvantages ofmixing combustion products with the recovered oil and gases.

In the present invention the heat transmission occurs practicallyexclusively within the material subjected to distillation, such as oilshale, so that the distillation gases are not exposed to a subsequentand undesirable action of heat.

The present invention is directed to a novel means for retorting oilbearing shale for the purpose of extracting the vapors. External-1yheated attrition resistant solid bodies such as steel or ceramic ballsare used for transferring heat to the oil shale. The invention includesthe use of a stationary drum retort equipped with an internal rotatingscrew which contains throughout its length perforated or slotted screwflights together with baflles designed in such a way that the solidbodies or balls are retained on the screw and do not fall through theslots or perforations'but the oil shale falls through. The oil shalewhich is crushed by action of the heated balls upon it is fed into thetop of the retort and by gravity falls down through the perforations orslots in the screw in the retort to the bottom where the carbonaceousresidue or shale coke is removed and may be burned to supply heat to theexternal heater which in turn supplies heat to the recycled balls. Theexternally heated balls flow by gravity from the heater to the bottom ofthe retort where the rotating screw picks them up and works them to thetop and out of the retort to a point where they flow by gravity back tothe external heater where they are reheated and recycled to the bottomof the retort. Proper baffles are present on the screw to retain theballs in their upward movement and to prevent the balls from rollingbackwards or toward the bottom of the retort. The screw can be driven byany means such as a variable-speed motor and the degree of heat transferor contact time between the balls and the oil shale can be varied byadjustment of the speed of rotation of the screw.

The apparatus of the present invention has numerous advantages. Thecountercurrent flow of hot balls and oil shale provides in combinationvery efficient heat exchange and grinding action on the shale. Theapparatus of this invention is simple to seal at the points where thescrew shaft enters and leaves the retort. The apparatus lends itself tovariable speed operation, thus making the degree of heat exchange easilycontrolled. The circulation of the balls from the retort through theexternal ball heating furnace and back to the retort can be accomplishedall by gravity and does not require an external lifting device' such asa bucket conveyor and the like. The connections for the shale enteringand leaving, the gas outlet connection and the connection for the ballsentering and leaving can all be made of very simple and rigidconstruction because the shell of the retort does not rotate or turn.

The invention will be readily understood as this description proceeds,reference being made to the accompanying drawing wherein is depicted aspecific embodiment of my invention. In the drawing the retorting vessel1' is an inclined stationary drum equipped with a rotatable screwmounted on the shaft 2, said shaft being secured by suitable bearing andseal means at the top and bottom 3 of the retorting vessel. The screw isequipped with openings 4 which are large enough to allow the shale tofall through but small enough to retainthe balls and cross baffles 5which carry the balls in an upwardly direction in the retorting vesselas the screw rotates. The cooled heat carrying solid bodies or balls arecontinuously removed from the retorting vessel and pass through conduit6 and are heated in the external heater 7 and the heated balls pass bygravity flow 8 to the bottom of the retorting vessel and enter theretorting vessel at the opening 9. In this particular illustration therotatable screw is driven by a driving means 10 which may contain a gearsystem 11 for varying the speed of rotation of the screw and the screwrotates in counter-clockwise fashion when in operation. As the hot ballsare moved upwardly in the retorting vessel by action of the rotation ofthe screw, they come in intimate contact with downwardly movingoil-shale 12 which may be externally preheated which enters the upperportion of the retorting vessel at 13 and the shale is ground to a finerparticle size and the oil is removed from the ground shale by pyrolyticaction of the hot balls. The balls move upwardly by action of the screwand bafiles and the crushed shale moves downwardly as it falls throughthe openings. The gas and oil vapors resulting from the pyrolysis of theoil shale are removed at points 14 and the spent shale or shale coke isremoved from near the bottom of the retort 15. The shale coke preferablyis used as fuel and is combusted with an oxygen containing gas such asair or oxygen alone in the burner 16 which supplies heat to the externalheater 7 and the flue gas from the burner escapes at 17.

Although less preferred, it is to be understood that the apparatus ofthis invention may also be used as a ball mill for grinding substanceswithout heat exchange or wherein a heated gas is used as the exchangemedium. In such cases the cool balls from the top of the retortingvessel are simply circulated by gravity to the ball inlet 9 thusby-passing the external heater 7 and are recycled through the retortingvessel. Such application wherein a heated gas serves as heat exchangemedium and the balls serve mainly to grind the heated oil shale is morefully described and claimed in the copending US. patent application ofMarlin U. Zimmerman, Jr., Ser. No. 320,451, filed Oct. 31, 1963, nowabandoned.

The solid bodies which serve as heat carriers in the present inventionare usually attrition resistant bodies in the form of balls, pebbles orshot of suitable size and specific gravity. The solid heat carrier maybe composed of inexpensive metals such as iron, steel, aluminum, highmelting lead alloys, and the like as well as refractory materials andparticularly ceramic materials which have relatively large heatcapacities and are not subject to oxidation or reduction. The particlesizes of the solid heat carriers usually vary from about 50 mesh toabout one inch in diameter. As was stated earlier, the balls must belarge enough so that they do not fall through the openings, which may beslots or perforations in the screw and it is proposed that the balls belarger than the shale particles, particularly after the shale particleshave been subjected to some grinding action.

Just prior to the time it enters the distillation apparatus theoil-shale may be preheated to a temperature in the range of from about400 to 600 F. Above approximately 600" F. pyrolysis of the shalecommences.

In the pyrolysis of oil-shale, for instance, a temperature of from about750 F. to 1800 F. and more preferably about 800 F. to about 1200 F. maybe employed within the reaction zone. The pressure is not critical andmay be atmospheric or a few pounds above atmospheric, in other words,sufiicient to overcome pressure drops in the system. The use of theapparatus of this invention for vacuum stripping operation is lesspreferred, but such use is within the scope of the present invention. Itis preferred in the operation of the apparatus of this invention thatthe oil-shale remains resident in the reaction zone for a suflicientperiod of time to effect the desired conversion.

The hydrocarbon oil recovered from the shale can be further processed atthe retorting site or may be shipped or pumped via pipeline to therefinery where it can then be converted to a volatile product and a taror coke. The volatile hydrocarbons are then treated according to thecustomary oil refining practice and separated into various fractions,such as normally gaseous hydrocarbons, gasoline constituents, gas, oil,tar, coke and the like, as desired, The fixed carbon or coke which isleft on the sand or spent shale is burnt to supply heat for the process.

While the preferred embodiment of my invention has been shown anddescribed, it will be understood that changes and modifications may bemade that lie within the skill of the art. Hence, I intend to be limitedonly by the appended claims.

I claim:

1. A device for the treatment of oil-bearing shales by means of thegrinding action of attrition resistant solid bodies which are broughtinto direct contact with the shale during its operation; said devicecomprising a stationary cylindrical drum fixed in an inclined position;said drum containing near its top an inlet for the introduction of saidshale, an outlet for the removal of gaseous products and an inlet nearthe bottom for the introduction of said attrition resistant solidbodies; said drum containing a centrally located rotatable shaftequipped with a screw, said shaft being secured by suitable bearing andseal means at the top and bottom of said drum; driving means forrotating said shaft; said screw being equipped with openings largeenough to allow the shale to pass through and small enough to retain thesolid bodies and said screw also being equipped with cross bafiiesadapted to carry the solid bodies in an upward direction in the drum asthe screw rotates; said drum having an outlet at the top for continuousremoval of said attrition resistant solid bodies and an outlet at thebottom for continuous removal of the treated shale.

2. The device of claim 1 wherein there is an external means fortransferring the attrition resistant solid bodies from the outlet at thetop of the drum to the inlet near the bottom for introduction of saidattrition resistant solid bodies ino the drum.

3. The device of claim 2 wherein said external means includes a heaterfor supplying heat to th attrition resistant solid bodies.

References Cited UNITED STATES PATENTS 843,599 2/1907 Hamrriatt 20l32 XR2,009,122 7/1935 Reed et al 2022l8 2,984,602 5/1961 Nevens et al 201-12FOREIGN PATENTS 848,644 9/ 1952 Germany.

MORRIS O. WOLK, Primary Examiner.

I. SCOVRONEK, Examiner.

1. A DEVICE FOR THE TREATMENT OF OIL-BEARING SHALES BY MEANS OF THEGRINDING ACTION OF ATTRITION RESISTANT SOLID BODIES WHICH ARE BROUGHTINTO DIRECT CONTACT WITH THE SHALE DURING ITS OPERATION; SAID DEVICECOMPRISING A STATIONARY DRUM CONTAINING NEAR ITS TOP AN INLET FOR THEINTRODUCTION OF SAID SHALE, AN OUTLET FOR THE REMOVAL OF GASEOUSPRODUCTS AND AN INLET NEAR THE BOTTOM FOR THE INTRODUCTION OF SAIDATTRITION REISTANT SOLID BODIES; SAID DRUM CONTAINING A CENTRALLYLOCATED ROTATABLE SHAFT EQUIPPED WITH A SCREW, SAID SHAFT BEING SECUREDBY SUITABLE BEARING AND SEAL MEANS AT THE TOP AND BOTTOM OF SAID DRUM;DRIVING MEANS FOR ROTATING SAID SHAFT; SAID SCREW BEING EQUIPPED WITHOPENINGS LARGE ENOUGH TO ALLOW THE SHALE TO PASS THROUGH AND SMALLENOUGH TO RETAIN THE SOLID BODIES AND SAID SCREW ALSO BEING EQUIPPEDWITH CROSS BAFFLES ADAPTED TO CARRY THE SOLID BODIES IN AN UPWARDDIRECTION IN THE DRUM AS THE SCREW ROTATES; SAID DRUM HAVING AN OUTLETAT THE TOP FOR CONTINUOUS REMOVAL OF SAID ATTRITION RESISTANT SOLIDBODIES AND AN OUTLET AT THE BOTTOME FOR CONTINUOUS REMOVAL OF THETREATED SHALE.